Splitwise MCP

A Model Context Protocol server that connects Claude to Splitwise, giving you natural-language access to your expenses, groups, friends, and balances.

[!WARNING] AI-developed project. This codebase was entirely built and is actively maintained by Claude Code. No human has audited the implementation. Review all code and tool permissions before use.

What you can do

Ask Claude things like:

• "What do I owe?"
• "Add a $50 dinner expense to the vacation group"
• "Split this hotel bill 60/40 with Sarah"
• "Who's in the trip group?"
• "Add Meredith to the household group"
• "Show me recent expenses"
• "Delete that duplicate expense"

Requirements

• Claude Desktop or Claude Code
• Node.js 20.6 or later
• A Splitwise account and API key

Installation

Option A -- npx (recommended)

npx -y splitwise-mcp

Add to your Claude config (.mcp.json or Claude Desktop config):

{
  "mcpServers": {
    "splitwise": {
      "command": "npx",
      "args": ["-y", "splitwise-mcp"],
      "env": {
        "SPLITWISE_API_KEY": "your-api-key-here"
      }
    }
  }
}

Option B -- from source

git clone https://github.com/chrischall/splitwise-mcp.git
cd splitwise-mcp
npm install
npm run build

Add to Claude Desktop config:

• Mac: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "splitwise": {
      "command": "node",
      "args": ["/absolute/path/to/splitwise-mcp/dist/index.js"],
      "env": {
        "SPLITWISE_API_KEY": "your-api-key-here"
      }
    }
  }
}

Getting your API key

1. Go to secure.splitwise.com/apps/register
2. Register an app (name and description can be anything)
3. Copy the API key from the app detail page

Credentials

Available tools

20 tools across 5 domains. All tools are prefixed sw_.

User

Groups

Friends

Expenses

Utilities

Troubleshooting

"SPLITWISE_API_KEY is required" -- set the environment variable in your MCP config or a .env file.

429 rate limit -- Splitwise has undocumented rate limits. Wait a moment and retry.

Tools not appearing in Claude -- go to Claude Desktop > Settings > Developer to see connected servers. Make sure you fully quit and relaunched after editing the config.

Development

npm test        # run the test suite (vitest)
npm run build   # compile TypeScript -> dist/

Project structure

src/
  client.ts         Splitwise API client (auth, request handling)
  index.ts          MCP server entry point
  tools/
    user.ts         sw_get_current_user, sw_get_user
    groups.ts       group CRUD and membership
    friends.ts      friend list and management
    expenses.ts     expense CRUD, comments
    utilities.ts    notifications, categories, currencies

License

MIT